Burial and exhumation history of the Labrador-Newfoundland margin and implications for hydrocarbon exploration

The stratigraphic record along the continental margin of Labrador and Newfoundland provides ample evidence for vertical movements both prior to and after break-up. In the offshore domain, several major hiatuses punctuate the stratigraphic record. Along Labrador and the Grand Banks, Lower Cretaceous rocks rest on Paleozoic rocks or Precambrian basement in parts of the area. Onshore Labrador, the presence of a Cretaceous outlier on Precambrian basement adds to the evidence of one or more events of exhumation that has removed pre-Cretaceous sediments on a regional scale. Over much of the Labrador shelf, Miocene deposits are absent, and we show evidence based on vitrinite reflectance and sonic data that indicate that Miocene deposits of significant thickness may have been present prior to uplift and exhumation. We also present results from a pilot study comprising apatite fission-track analysis (AFTA) data that reveals a Phanerozic history involving a series of burial and exhumation episodes. The pilot study is a forerunner for a study of the onshore and offshore domain with three components. (1) A thermochronological study based on samples from outcrops and from onshore and offshore boreholes. (2) A stratigraphic landform analysis of the onshore study area based on mapping of denudation surfaces that will provide evidence of vertical motion using cross-cutting relationships between the denudation surfaces and stratigraphic constraints. (3) An integrated interpretation of the geological, geomorphological and thermochronological data to provide a coherent model of the timing and magnitude of the vertical movements along the margin both prior to and after break-up. Failure to account for greater depths of burial prior to exhumation may lead to serious underestimation of the petroleum resource maturity and to erroneous estimates of the timing of hydrocarbon generation. Uplift and exhumation may also lead to changes in migration routes and affect hydrocarbons present in reservoirs. Insights into the uplift history of a margin are important for understanding the sourceto- sink system of sediment input into offshore basins.